|About multi-store and domains|
|If you see the following message, there are 3 possible main causes:
Scenario 1: You have a parent scope configured.
It isn't necessarily an error message, if you see this message in either a store view or website scope, and this scope is inheriting the configuration from its parent, the message is ok.
It just means the specific scope you are seeing has its data being sent by a parent scope (either a website or the default configuration), so if this is the case please ignore the message, there is nothing wrong.
Scenario 2: Using multi-store with the same domain under a Mailchimp account.
When you are under multi-store instance it is required to have different domains for each scope you want to associate with a Mailchimp store.
If one scope has been associated with a Mailchimp store, no other scope under the same domain will be allowed causing any new scope being configured to fail generating this errors.
1. Use a different domain on each store view. (en.domain.com. es.domain.com)
2. Enabling store codes: https://php.quicoto.com/how-to-add-store-codes-in-url-magento/
In this case the stores will be allowed to be created but only the first one will have the full availability of the Mailchimp features.
Stores created under the same domain but different path will not be able to use Mailchimp's Pop up nor Product Retargeting emails.
Scenario 3: Orphan Mailchimp Store
In case none of the above apply to you. There is probably an orphan store in Mailchimp not allowing you to create a new store under the same domain. Since this store is not wanted unless it is associated to your Magento it is necessary to delete it in order to allow a new store with the same domain to be created and correctly associated to Magento.
This can be done at mailchimp.com going to 'Connected Sites' on the top right menu. Select the unwanted store, click on the 'Disconnect' button and re-save the configuration on Magento to get the new store created.